# Tag Info

### Importance Sampling of Environment Maps

This is not a full answer, I would just like to share the knowledge I obtained by studying two of the papers mentioned in the question: Steerable Importance Sampling and Practical Product Importance ...
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### Importance Sampling of Environment Maps

Disclaimer: I have no idea what is the state of the art in the environmental map sampling. In fact, I have very little knowledge about this topic. So this will not be complete answer but I will ...
• 446
Accepted

### Image based lighting, tangent space coordinates, and optimization

Yes, you do need to transform the fetch direction into the space of the cubemap. If you could somehow figure out the fetch direction in the vertex shader, then you could do the transformation there ...
• 3,842

### How Image Based Lighting is applied to indoor scene?

There's two main things it seems like you've not understood correctly. IBL is for indoor scenes and outdoor scenes In the early days when IBL was hot, the Uffizi light-probe was probably the most ...
• 6,450
Accepted

### PBR : Understanding the right part of Split sum integration of specular IBL

1)What is the V vector? How did they compute that It's the vector toward the camera (view vector), i.e. direction of the reflected ray. The lookup table they're building is parameterized in terms of ...
• 23.6k
Accepted

### Integrating BRDF using Importance Sampling

Think of this way: when integrating uniformly over the hemisphere, it's like you are importance-sampling with a constant pdf of $1/2\pi$. The multiplication by $2\pi$ at the end, then, can be seen as ...
• 23.6k
Accepted

### Problem sampling uniformly envmap with GGX

How are you randomizing the samples you take? It looks to me like maybe the random values are the same across all pixels in the image, which would explain why you see 10 coherent bright spots when you ...
• 23.6k
1 vote

### PBR : Understanding the right part of Split sum integration of specular IBL

I recommend to ignore my post (however I consider papers that I've sent valueable) and read post of Nathan Reed, which is much better in explaining this problem! I'm still a junior when it comes to ...
1 vote
Accepted

### Weirdly looking diffuse irradiance map

I've actually managed to find problem thanks to @PaulHK, thanks! I decided to pass which face I am currently working on and setting then coordinates manually per face. It is awful but it works rather ...

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